1. Field of the Invention
The present invention relates to a Short Message Service (SMS) of mobile communication terminals, and more particularly to a method for transmitting a character message in mobile communication terminals during a conversation by telephone.
2. Description of the Related Art
In general, Short Message Service (SMS) refers to a personal communication service of a kind which allows for communication of voice or character messages between mobile communication terminals of GSM (Global System for Mobile Communication), CDMA, or PCS types. Short Message Service is used, for example, when direct communication by telephone between users of mobile communication terminals is impossible or inconvenient. For example, the user of the mobile communication terminal of the calling and/or called party may be located where he or she has difficulty communicating by telephone, as in a conference hall, where carrying on a voice conversation would be disruptive, or where there are privacy concerns. Although a mobile communication terminal of a called party may receive an incoming call from a mobile communication terminal of a calling party, the called party may have difficulty speaking directly by telephone with the calling party in response to the reception of the incoming call. Also, for example, where an emergency call is required, although the mobile communication terminal of the calling party may transmit an outgoing call to the called party terminal to establish a speech path or a channel, the calling party may have difficulty in directly speaking by telephone with the called party. In such cases, the mobile communication terminals of the calling and called parties may resort to transmitting and receiving character messages by using the SMS. Accordingly, the calling and called parties can communicate with each other using character messages even though those character messages are limited in length.
However, the prior art SMS makes it impossible to transmit or receive a character message during the conversation by telephone between the mobile communication terminals of the calling and called parties. That is, SMS is a personal communication service for exchanging messages between the calling and called parties who have trouble speaking directly by telephone, but it is relatively limited because it is not supported during a telephone conversation. For this reason, the users suffer an inconvenience of always having to access SMS always after hanging up the receiver while conducting a conversation by telephone when it becomes necessary to send a character message.